Fuel-injection valve



June 19, 1928.

P. A. LAWRENCE FUEL INJECTION VALVE F'ld Sept. 17, 1925 Patented June19, 1928,.

UNITED STATES PAUL ANDREW' LAWRENCE, OF GRAND ISLAND? NEBRASKA.

FUEL-maritimen vanvn.

Application le September 17, 1923. Serial No. 663,288.

My invention relates to a4 fuel injection valve for constant pressure,internal combustion engines and, particularly, to a type of constantpressure engine employing an 5 air chamber into whi-chthe compressed airof the compression stroke is delivered during the latter part of thecompression stroke and from which this air is again inducted into thecylinder during the early part of l the power or combustion strohe.

lVith proper modification, this valve may also be employed in any solidinjection type of oil engine in which a close approach to a constantpressure thermal cycle is desired.

Referring particularly to the type of constant pressure solid injectionoil engines employing an air chamber and `a non-return valve between theair chamber and the cylinder, and which engine is illustrated in Figure5 oit' the drawings, it will be seen that this type of engine requiresthat the oil be injected at such a rate that the pressure does not tendto rise in the cylinder. If the oil is injected at a higher rat-e, thereis nothing to prevent the flame or products of combusti n from passingthrough the air chamber va ve and into the air chamber.

Although there is nothing seriously harmful for the liame to enter theair chamber, for best 'operating results the llame should always bedirected toward the cylinder, so that the products of combustion arecontinually passing on out of the way of succeeding yportions of oil asthe piston advances and thereby insure perfect combustion. It thisprocess is not approximately carried out, imperfect combustion resultsbecause the products of combustion of the earlier portions of oil becomemixed with the pure air in the air chamber.

The air from the air chamber flows into the cylinder by induction; thatis, as the piston moves out from the cylinder head, it tends to lowerthe pressure in the cylinder and the air from the air chamber naturallyflows through the open valve into the cylinder as fast as the pistonadvances. Now, as the piston starts slowly and ac'- celerates its speedas it advances, so the air entering the cylinder flows in with anacceleratin velocity in exact proportion to the accelerating speed ofthe piston. It is clear that the fuel should be injected at the samerate as the flow of the air, which is equivalent to saying that theJfuel should be injected at an accelerating rate in correspond. encewith the piston travel.

In the practical operation of this type of engine,it is not desirable toinject as much oil as the air will consume, but to leave a considerablequantity of excess air in the products ot combustion to oxidize thecarbon deposits on the piston and to give the engine a higher thermalellicienc Fur= thermore, there is considerable sel regulation going onin the way of automatically adapting the combustion to the fuelinjection rate by a raising or lowering of the pressure, which changesthe density of the compressed air and, therefore, its relation to therate of piston travel. For these reasons, it has been found that the oildoes not have to be injected precisely in accordance with the rate otpiston travel, but only approximately so.

ln a single cylinder engine the fuel pump may be so designed as todeliver oil to the injection valve at an accelerating rate of iiow and,therefore, a. simple valve is all that is required. But, with a multiplecylinder engine, it is desirable to use a c0nstant pressure pump,supplying the valves with oil at constant pressure and using a valve ofsuch construction that the fuel will be injected at an acceleratingrate.

ln my invention, this is accomplished in the manner as shown by thedrawings and the description which follows. It must, however, beobserved that the details of construction are not essential, as thereare numerous ways in which thesame idea can be carried out, but theprinciple, as set forth in the claims taken in connection with apractical example, as shown in the drawings, is to be taken asrepresenting the scope of the invention.

Referring to the drawings:

Figure l is a sectional view of the valve, showing all of itsparts. Thesection plane passes through the axis of the valve, cutting all theparts upon a vdiametrical plane, eX- cept the parts a, w21, wl, a5, al,a, at", a, c, @29, at?, u32 and 133, which are shown in elevation, andthe part m9, which is shown partly in elevation and partly in Section.

In this figure, the by-pass, mah is shown diametricall opposite theinlet connection, 6545, in or er to simplify the drawing, but it is moreconvenient to arrange it on the side of the valve body as shown inFigure 5.

Gil

Figure 2 is a separate view of the part, ai, taken perpendicular to itsassembled view in Figure l.

Figures 3 and 4 are two views of the part, (L22, also shownperpendicular to its assembled view in Figure 1.

Figure 5 is a typical illustration of the valve in position in theengine cylinder with those parts of the engine with which it cooperates.The view is taken upon a section plane passing through the cylinder andair chamber perpendicular to the crank shaft and shows the piston andvalve in elevation.

No fuel pump is illustrated because any pump will answer which iscapable of furnishing a nearly constant pressure oil supply.

Referring to Figure 1, the valve will be seen to consist of a housing,(w, with four openings. The upper and lower openings are provided withpacking glands, and (rl. The side outlet to the right is connected tothe fuel pump and the side outlet to the left embraces the by-passdevice, (1431.

The bore of the housing is much smaller near the middle, just largeenough to pass the rod. Directly above this contraction is a third setof rod packing, (LT, held in place by the gland, (140. This arrangementdivides the valve into an upper and lower chamber 'separated by thepacking, (147, and made tight at the ends by the packings, (1)2675 G3535The rod, a, passes through the three packings and is hollow, with acontraction of the bore at (110. Y

Into the upper end is screwed th'e nozzle, (512, and into the lower endthe plug, (a. The rod, (z, is slotted at the sides, (120, a sufficientdistance so that it may freely slide up and down the full amplitude ofits stroke without striking the member, 01.21, which passes throughtheslots. One or more holes are drilled through the side of the rod ata4 to admit the oil into the interior. A plunger, (l, is closely littedto the interior bore of the rod, (1, and forms a valve by seat-ingagainst the contraction, a1.

This shuts the oil from the nozzle, e112 The plunger, (59, is alsoslotted to receive the member, (121, but the slot is no longer than thedepth of the member, (Ll, and is, therefore, securely held in place byit. The lower portion of the plunger, (LD, is hollow to receive anon-return back pressure valve comprising a ball, (17, resting upona'seat, (z, which screws into the plunger, and a stiff spring, (LU,bearing upon the ball, (z". A port, m9, completes the communicationbetween the lower and upper chambers.

Just below the plunger, a2 is a spring seat having a stem, (15, bearingagainst the lower surface of the ball, A spring, (535, is pressed upwardfrom below by the seat, 0.47, and the plug, a. Washers, (Lm, are used toadjust the tension of the spring.

The member, (121, is securely seated in the slot, (123, Figure 4, andrests upon the upper surface of the part, a"'.

In order to prevent the oil from leaking out through the threads of(LEY, the member, (ngz, is turned down near its upper end, a ring ofpacking, (124, placed over it and held down by a metal ring, ags. Itwill be seen that when the gland, (LQT, is tightened it firmly forcestogether the parts, Claim, 4(2477 ia/227 und ia-4G77 and 586111.81),Seats the member, (LG, against the valve body. The oil can only passfrom the lower chamber to the upper chamber through the valve, (zl,against the tension of the spring, (z, minus the tension of the spring,(134,

The spring, (zf, bears upon the ball, (17, with a constant load, whilethe spring, (13, is so adjusted as to bear very lightly upon the underside of the ball, (17, when the rod, (1, is down, but as the rod risesthe tension of the spring, a3*, rapidly increases so that when the rodhas reached the height of its travel it bears the ball upward with aboutas much force as the spring, (1,10, bears it downward. The resultof'this combined action is that, when the rod is down, the back pressureagainst the oil is a maximum; while, when the rod is up, the backpressure is nil.

The size of the plunger, is so chosen as to give the requireddisplacement with due regard to the quantity of oil to be injected.lVhen the rod, (1, rises, the plunger, (Lf', causes a negativedisplacement in the upper chamber because it is stationary while the,rod, (z, is movable. Then the rod, (n, falls, the plunger, (zf', causesa positive displacen'lent tending to force the oil out through thenozzle, because it cannot pass back through the valve, (l.

Now, the size of the plunger could be so nicely chosen as to exactlymeet the requirements of the quantity of oil to be injected, but this isim )ractical because of leakage and other variable conditions and soitis made with an ample factor of oversize and a by-pass provided for thesurplus oil.

In order to bring the oil from the upper chamber to the by-passl a port.(La, is formed in the valve housing which communicates with the port, a.The bypass communicates with the lower chamber through the port, a1".

The by-pass consists of a ball, (LU, held to its seat against thepressure in the upper chamber by the spring seat, (130, the spring, am,and the plug, (1,33. The members, 032, are washers for adjusting thetension of the spring.

The nozzle member, (112, screws into the rod, (1, and seats against ashoulder on the IUD rupon the conical end of the plunger,

nozzle. It has al hole, a11, drilled :from below to meet the holedrilled crosswise at an angle and contracted at the outlet to form anozzle. v

A spring, m2, seats the rod, in firmly Mag, and prevents any oil fromentering the nozzle until the rod, a is pushed upward and uncovers theport, al

The valve is connected to a constant pressure oil supply of highpressure through Lthe 7pipe, @1, and connections, a2 and Figure 5 is atypical installition of the `valve within the engine cylinder.

This engine has an air chamber formed within the cylinder head.' Thevolume of this air chamber is preferably a half or a third of the pistondisplacement. The air chamber is closed by a non-return valve, 5, heldto its seat by a light spring located in the spring case, 5.9, bearingupon the plunger* 461.77

The cylinder head also has a combustion port, (11, milled in its lowersurface, forniA ing a passage tor the air between the cylinder and theair chamber.

The air chamber is connected to an air bottle, not shown, through thepipe, 029, for starting the engine. llilo air compressor is requiredfor. the engine normally replenishes the air bottle -from the air itcompresses.

The fuel in'ection valve a/v seats into a receptacle formed in thecylinder and isl held up in place'by a suitable yoke, not shown, underthe collar of the valve.

The piston clearance is reduced to a minimum and does not determine thecompression pressure of the engine. The compression pressure isdependent upon the fuel pressure.

By means of a cam and follower, not

shown, or other suitable means, the valve rod, in is given a variablethrowl in accordance with the load on the engine.

The above description defines the uses of the different parts. Tofurther elucidate the invention, I will describe in detail the operationof the valve and its relation to the type of engine illustrated. y p

To start the engine, it is turned over until the crank has just passedthe upper dead center. The piston is now in approximately the positionshown in Figure 5, viz, just beginning its power stroke. The air chambervalve, 5, is slightly o en so that air can freely enter the cylin er assoon as air is admitted to the air chamber. The instant this is done thepiston is driven down with much force. The valve, 5, is held open forabout one-half stroke when starting but the cut-oil' is reduced by handor governor assoon as normal operation is attained. Exhaust takes placeat the end of the stroke as usual and a charge of pure air is driven in.On the upward stroke, this air is compressed until it reaches a pressureequal to the .pressure in the air chamber. This occurs near the end ofthe stroke, for the pressure in the air chamber is approximately thesame as the compression pressure under which the engine normallyoperates. As the piston cont-inues its motion, it forces this compressedair through the valve, 5, into the air chamber. iVhen the piston hasreached the end of its stroke, most of the compressed air has beendelivered into the air chamber. Just as the piston starts downward onthe power stroke, the cani mechanism (not shown) raises the valve rodwhich, in turn, lifts the valve, 5, and permits the compressed air to beinducted back into the cylinder at an accelerating rate. The valve alsoinjects the oil at an accelerating rate as follows:

' Assume that the engine is operating at a compression pressure of 300lbs. and that the fuel injection begins with a pressure of 100 lbs.higher and ends with a pressure of 5U() lbs. higher than the compressionpressure in the engine cylinder. The ituel injection should not commenceat too low a head, otherwise the oil will not be divided tine enough forproper combustion. Assume that the spring, m9, has `a tension such thatit requires a dillerence in ressure of 200 lbs. per square inch to o )ent 1e valve .a, and that the spring, naif is so -chosen that when therod, fa, is down its pressure against the ball, al is nil and when therod is near the upper end of its stroke its pressure on the ball. is thesame `as that of the spring, aut

Further assu-me that the spring, abz is so adjusted that it requires adifference of pressure of lbs. per square inch to open the valve, e152Under these conditions the oil pressure in the pipe, a2 and low-erchamber of the valve housing would be 300 lbs. yhigher than thecompression pressure, or 600 lbs. gauge. New, the instant the rod, (L,begins to lift it uncovers the port, a1?, and as the back pressureoi'l'ered by the valve, a7, is 200 lbs., the oil will issue fromthenozzle under a head of lbs. per square inch. As the valve rod rises, thehaelt pressure ot the valve, m7, grows less and becomes nil at the endof the upward stroke of the valve rod. The head at the nozzle is,therefore, raised from 100 lbs. to 300 lbs. per square inch during theupward `stroke of the valve rod. As the rod starts downward, thedisplacement of the plunger, a, comes into play, the valve, e2 closes,and the pressure in the upper chamber rises until it reaches a pressure200 lbs. higher than the pressure in the lower chamber when the valve,ali opens and luy-passes the surplus. lf the size of the plunger isproperly chosen,

lll)

the pressure rise during the downward stroke of the rod, in is quitegradual and the by-pass does not open until the rod is nearly down.

It will be seen thaty the head at the nozzle was gradually increasedfrom 300 lbs. to 500 lbs. per square inch on the downward stroke of theplunger. The entire range of pressure head at the nozzle is, therefore,from 100 lbs. to 500 lbs. per square inch during the combustion periodof the engine. Changing the tension or the degree of elasticity of thesprings makes it possible to secure almost any characteristic in therate of injection of the. fuel. When once the adjustment has been made,there is no further need of readjusting these parts afterward.

The valve is so constructed as to avoid air pockets and, therefore,there is no chance for an accumulation of oil in the upper chamber undera pressure that would disturb the proper working of the valve, asdescribed.

lVhen the engine is operating at less than full load, the valve rod doesnot rise so high and, therefore, the back pressure of the valve @7, isnot brought to zero. Nevertheless, the action of the plunger, a2 quitegracefully smoothes out this discrepancy and, as the excess of air isnow greater, the fuel does not have to be injected with the precisionwhich is necessary when operating at full load.

There is another factor which I may here mention that makes thecombustion more gradual than the fuel injection, and that is the degreeof division of the oil.

The higher the head under which the oil is injected, the finer thedivision and the more rapid the combustion. The fuel injection endsunder the highest heads and, therefore, the combustion is the most rapidat this time. This is just what is needed for economical results.

As usual, the engine normally fires by spontaneous ignition. In a coldengine, the oil may be fired by a spark plug, by preheating the headwith a torch, or by raising the compression the required amount.

I claim:

1. A fuel injection valve, comprising a. movable rod; a displacementdevice; a nonreturn back pressure valve; means of reducing the backpressure through the movement of said rod and means of injecting thefuel through the displacement device.

2. A fuel injection Valve, comprising a movable rod; a displacementdevice; a. nonreturn back pressure valve; a spring loaded by-pass; meansof gradually reducing the back pressure through the outward motion ofsaid movable rod; means of injecting fuel' through the displacementdevice by the re turn motion of said movable rod and means of limitingthe injection pressure by the by-passing device.

3. In combination with a constant pressure fuel supply a fuel injectionvalve comprising two chambers; a movable rod; a displacement device; aback pressure valve; a by-pass valve; means of reducing the backpressure through the movement of the said rod in one direction and meansof injecting the fuel through the displacement device by the movement ofthe rod in the opposite direction.

4. A fuel injection valve having a valve rod traversing two separatechambers in the valve bod a non-return valve between the two chambers; aspring hearing on said non-return valve; and a second spring bearing onsaid non-return valve, in opposition to said irst spring, with variableintensity dependent upon the position of said valve rod.

5. A fuel valve having a valve rod traversing two separate chambers inthe valve body; a displacement rod; a spring loaded valve; a spring,operated by said valve rod, acting in opposition to said spring loadedvalve; and a by-pass valve connecting said chambers.

6. The combination of a fuel injection valve with a constant pressurefuel supply comprising a valve body having two chambers; a valve rodtraversing said chambers; a displacement rod located within said valverod; a spring loaded valve opening toward the nozzle; a spring acting inopposition to said spring loaded valve, operated by said valve rod; anda spring loaded by-pass connected between the two chambers and openingtoward the oil supply.

7. A fuel injection valve comprising a housing having two separatechambers; a hollow movable rod; a nozzle at one end; a valve seat belowsaid nozzle; a stationary rod within said movable rod seating againstsaid valve seat; and a non-return valve, between said chambers, openingtoward the nozzle.

PAUL ANDREW LAWRENCE.

